This may have been posted before but I see questions about it everywhere: How do you stop your horse following you into gunfire when it's not getting scared of it? (this is probably another glitch)

The answer?

Equip your fist, and without pulling the left trigger point yourself at the horse and pull the right trigger, you'll give the horse a harmless push which will make it run off. 

sidenote: this same push can be used on civillians to start a fight, or clear a poker table (all players run away, but run around the block and one or two will be back which makes getting the US army outfit faster than cheating/dueling.

Edit: I agree with the staff: this game is incredibly rotten about conveying shit like this! The mission "Justice in Pike's Basin" (the one shown in the quicklook) would've been an easy way to show this if the marshall said "Slap the asses of your horses lest they catch a bullet boys" prior to heading into the combat part of the mission.

Sweet, good tip!

The better idea? 
 
Shoot that fucking horse, because what good is he if he's going to be running in front of your gun?  He should stop being so goddamn stupid.

" The better idea?  Shoot that fucking horse, because what good is he if he's going to be running in front of your gun?  He should stop being so goddamn stupid. "

" The better idea?  Shoot that fucking horse, because what good is he if he's going to be running in front of your gun?  He should stop being so goddamn stupid. "

I bought a horse from the general store and have the certificate permanently in my inventory. If he dies, I resummon him with the certificate. What is the downside of my horse dying?

wow, i never realised that in my whole 40 hour playthrough. Would have been pretty useful godamnit

I only had that problem once where I was in a heavy fire fight where theres more than 10 guys all shooting at you and my horse is standing in my way. I was like FUCKING MOVE HORSE! and my cats ran out of the room. Then he died and I was like NOOOOOOOOOOOOOOOOOOOO

Great, now this forum will be FULL of stickied threads too, making navigation more of a pain. I wish we could turn stickies off.

If my horse gets in the way, I shoot it in the face. I already have the trophy.

If ever a game needed horse armour DLC
 

" I don't know why but my horse keeps dieing for stupid reasons.  One time i whistled for it and it jumped off a cliff above me, plummeting to it's death.  Another time i was re-capturing a wagon for someone and i accidently backed into my horse and....boom, it just collapsed right there.  I finally gave up and bought the deed for a new Kentucky Saddler because i figured it'd be less annoying than reloading the game everytime my horse died.  Anyone else have their horse die for non-combat related reasons or do i just have really stinkin luck?  "

" If ever a game needed horse armour DLC
 

"

" If ever a game needed horse armour DLC
 

"

My horse has never died before (got the Spurred to Victory trophy without realising it), until it decides to ride off the cliff into the river upon my whistle.

My horse never died. Thank god.
I've tried shooting it, and running off cliff with it (I died as well, maybe that's why it's not counting), and letting it being hit by enemies...
And yet I still got the achievement.
And then I killed it as a celebration.

This may be a breakthrough for me...

Shot my horse for the first time last week.  Didn't know at first what happened.  Horse crumpled to the ground, and then I see a prompt  about losing honor!  I was like WFT just happened??!

Ive accidentaly shot my horse more times than its ever been hit in a fire fight, good tip though

I was in Thieves Landing and whistled for my horse. I'm watching it come, running at full speed, from far away. Running running running. Now it is going super fast. It gets to where I am. Keeps running. Catapults straight into swamp, neighs, then drowns. Sigh.

I got into a duel at Armadillo and when I entered the dual-mode and was teleported to the middle of the road, my horse was standing about a meter in front of me, blocking my view of the enemy.  I figured the horse wouldn't register with the game since it was a duel and therefore, there are only two things that the game should allow to be shot, so I painted my targets in the middle of the screen on the horse where I thought my enemy was standing.  Oh how wrong I was.  In this duel, I shot my horse about 15 times and kept shooting even after it was on the ground, giving me a clear view of the enemy, at which point said enemy got me once in the face.